Use try and catch when working with JSON.parse() to handle exceptions

Use JSON.parse(data) to validate e.g. received content. Throws a SyntaxError if JSON.parse() can't handle it because it is invalid.

// syntax error - need try and catch to handle it
data = '{"blah": 1 ,"foo": "II", "bar":"three}';

try {
   d = JSON.parse(data);
}  catch(e){
  console.log("instance:",e instanceof SyntaxError); 
  console.log("message:", e.message);
  //console.log("name:", e.name);
  //console.log("filename:", e.fileName);
  //console.log("lineNumber:", e.lineNumber);
 //console.log("columnNumber:", e.columnNumber);
  console.log("stack:",e.stack);
}
/* output 
instance: true
message: Expecting a valid value, got UNFINISHED STRING
stack:  at line 1 col 31
{"blah": 1 ,"foo": "II", "bar":"three}
                                  ^
*/